The Warriors' proposal for the S.F. waterfront site includes a 17,500-seat arena on the southeast corner of Piers 30-32, shed-like retail buildings along the Embarcadero, and 8 acres of terraced plazas in between.

Photo: Sn¿hetta And AECOM/Golden State

The Warriors' proposal for the S.F. waterfront site includes a...

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The construction would be paid for by the team, which would get a long-term lease from the city.

Photo: Sn¿hetta And AECOM/Golden State

The construction would be paid for by the team, which would get a...

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The Golden State Warriors' arena proposal for the San Francisco waterfront. Proposition B would limit high-rise development.

Photo: Sn¿hetta And AECOM/Golden State

The Golden State Warriors' arena proposal for the San Francisco...

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The Golden State Warriors' arena proposal for the San Francisco waterfront includes a 17,500-seat venue on the southeast corner of Piers 30-32, warehouse-like retail buildings along the Embarcadero, and roughly eight acres of terraced parks and plazas in-between.

After months of speculation, details are emerging about the arena that the Golden State Warriors want to build on San Francisco's Embarcadero - how it might look and what it might cost city government.

The team is proposing a 17,500-seat glass-covered arena on the southeast edge of Piers 30-32, with retail buildings along the Embarcadero and 8 acres of terraced plazas in between. Beneath the plazas would be 630 parking spaces.

The arena's height would be 135 feet, roughly the same as the top of the upper deck at AT&T Park. The design and finance plans, which are being presented Tuesday at a community meeting at the Delancey Street Foundation, also include such water-specific uses as kayak docks and a fireboat landing, part of the effort to win state approval for the project that the team seeks to finish in time for the NBA's opening day in 2017.

Traffic, crowds, recreational space and views are among the top concerns nearby residents have about the arena, which Mayor Ed Lee has called "my legacy project." As it seeks approvals, the team appears to be following the lead of the nearby Giants ballpark, which was built with private funds after voters defeated four referendums between 1987 and 1992 that sought public financing for a Candlestick Park replacement.

The conceptual framework of a financial deal between the city and the Warriors is a variation on the principle that the city provides the real estate and the team builds the venue.

"It is a fairly simple deal that is almost the exact same as the deal for AT&T Park," said Nathan Ballard, a Warriors spokesman on the project.

The ballclub would be given a 66-year lease for the pier, the longest allowed for port property, city officials say.

Piers need work

The team in return would build and pay for the arena and other buildings as well as the open spaces. It would be the team's responsibility to strengthen the dilapidated piers, an endeavor that city officials say would cost an estimated $120 million.

The proposed deal calls for the city to reimburse the team up to that amount for infrastructure upgrades.

The city's financial liability would be capped there even if the rehabilitation costs exceed that, said Jennifer Matz, the point person for Lee's administration on the project.

All told, the arena and adjacent development are projected to cost $1 billion, city officials said.

In terms of how the proposed project would reshape the 13-acre pier, architects on Monday emphasized their effort to expand public space along the waterfront.

Pedestrians would approach the arena from a large plaza along the bay on the southwest edge of the rebuilt piers. Terraced steps and ramps would rise to a second plaza inside the site, with shops on the west and the arena concourse on the east. The final open space would be north of the arena, a large landscaped area 45 feet above the bay.

"These piers are part of the bay and part of the city. They don't belong to one or the other," said Craig Dykers of Snøhetta, the project's design architect. "We're aiming to connect these two worlds together."

Bridge 'a centerpiece'

The spaces would form a sort of internal pedestrian street within the new complex, culminating in a view of the westernmost tower of the Bay Bridge: "The bridge is a centerpiece to the design," Dykers said.

Based in Norway and New York, Snøhetta also is designing for the new wing of the San Francisco Museum of Modern Art. The firm was selected by the Warriors in August as part of a team with AECOM, a much larger firm with experience at arena design.

The focus so far is on the layout of the site rather than the look of the buildings, the architects conceded. But the idea is an arena and concert venue that would be wrapped in glass. It also would be slit along the side to allow for an outdoor concourse ramp upward, part of the project's public space.

There are even fewer details about what would occur across the Embarcadero at Seawall Lot 330, a roughly triangular parcel that would also be developed by the team.

That site, currently a parking lot, was recently appraised for just over $30 million and could be used for retail, condominiums and, potentially, a hotel, Matz said.

2nd lot could pay debt

Under the current framework, the sale of that parcel is one of three sources the city can tap to repay the $120 million. The other two are rent credits of almost $2 million annually for the arena; and a portion of property taxes from development on the two parcels over the next 30 years, projected to be about $6 million annually, Matz said.

Once the city repays up to $120 million for rehab work, any money from those sources would flow to port coffers.

The terms of a repayment schedule remain to be negotiated, Matz said, and the city could issue bonds that would be paid back using a portion of the property tax from the development, similar to how the city helped finance infrastructure upgrades for the Giants' ballpark.

Under the deal, the city would also get a 1 percent transfer fee on the resale of future condos at the site after the initial sale.

If successful, the proposal would transform a slice of the city's waterfront that for decades has defied efforts to develop it, most recently when a deal fell through last winter with America's Cup regatta organizers led by Oracle CEO Larry Ellison.

"We really learned our lesson from America's Cup," Matz said. "This is a much tighter deal that is much more contained and constrained to the value that is being created by the Warriors."

Initial focus rightly on bay, not buildings

It's much too early to say whether the Warriors arena project should fill a 13-acre pier just south of the Bay Bridge. But the architects have come up with an approach that redefines what the Embarcadero could be.

The idea is to sculpt Piers 30-32 as a multitiered environment focused on the Bay Bridge, with the arena as an imposing but not overwhelming presence on the east. There'd still be views through the pier from Brannan Street and the vicinity of the Giants' ballpark; there also would be an ascending set of plazas, a procession of spaces designed to draw you in.

This inventive, almost geological approach is a hallmark of the work of Snøhetta, the design architect for the $1 billion complex. The firm's Oslo Opera House has hints of an iceberg emerging from the sea, with a rocky slope open for the public to explore. Its design for the new wing of the San Francisco Museum of Modern Art is like an eroded ridge that is entered by a raised path in the middle of the block.

But the artistic flourishes are practical, too.

Here, the upper plazas would sit atop 630 parking spaces. Those spaces also would be hidden by a pair of shed-like buildings along the Embarcadero that would contain retail space but be no taller than the existing historic structures at Piers 26 and 28.

The diagonal procession of plazas adds variety to a huge rectangular site that could hold five Union Squares. They'd be almost entirely free of shadows, another plus. Strollers in search of a more conventional encounter with the bay could follow an Embarcadero-level path along the edge of the pier, similar to the waterside walkway at AT&T Park.

Finally, placing the 17,500-seat arena in the southeast corner means it won't block the vistas from any nearby streets. Nor would it seem to scrape the bottom of the Bay Bridge, a worst-case scenario if a more conventional arena was dropped into place.

Again, the plan deserves all the scrutiny that the coming months will bring.

Setting aside the legitimate issues of traffic and crowds, we need to see a much more detailed architecture. The idea may be to wrap the arena in glass, but it will still be the largest structure on any pier along the bay. The ascending plazas sound intriguing. The reality could have the feel of a theme park.

There's also the question of what might be proposed for Seawall Lot 330. Nothing has been released, and that's where the Warriors meet the South Beach neighborhood.

So all this is nothing more than a start. But it's an intriguing start. Best of all, it understands that the Embarcadero doesn't need big buildings. It needs enticing connections to the bay.